Me personally I only use a backpack for very long trips.
I prefer to work out of cases (especially with the tech cam). The handling is much better for me.
When traveling by car with intermediate stops for walks of a few kilometers (I guess this is more or less what you guys do on a PODAS workshop) I use my cases with an attachable backpack system… see for instance here: http://www.b-w-international.com/index.php?option=com_facileforms&Itemid=66&lang=en
A mid sized Pelican case should fit into the B&H backpack thing.
Downside: it's of course a bit heavier than a dedicated backpack.
Upside: you can take the case out of the backpack and leave the backpack on your back while shooting… so you don't have to put down the backpack in the dirt (which can be really annoying when you're in mud or when it's raining). Too, you can use the case to stand on it if you shoot from a higher camera position (not kidding… I do that quite often).